Many auxiliary electrical generators function as standby units to provide AC power when the power from the utility AC grid is interrupted. The standby generators are often equipped with sensors that sense the absence of AC power from the grid and are started to thereby provide supplemental AC power to the home, office, building or other facility. Many facilities that provide necessary services have standby generators so that such services can continue to be provided. Hospitals and telecommunication providers are examples where the use of standby generators are utilized. Many standby generators are powered by engines that use gasoline or diesel as a fuel. It is not economical to use diesel or gasoline-powered engines to drive generators as the cost of operation due to maintenance and fuel far exceeds the cost of electricity obtained from utility providers.
The acceptance of standby generators relates to the emergency need for electricity, rather than the cost effectiveness of such equipment. In other words, in many situations, the need for electrical power overrides any concern for the cost of providing power in emergency situations. Even at the homeowner level, the cost of electricity delivered by standby means is less important than the comfort provided by the supplemental electricity when the power grid is unable to provide the same. But, the continued supply of AC power to a home when the grid fails, or during a brownout, is a function of the ability of the homeowner to pay for the standby equipment, and is not related to efficiency or cost payback. Accordingly, the luxury of having heat and cooling in a home during a power grid outage is available to those few who can easily afford the standby equipment.
The utilization of engine-driven generators by homeowners is not widespread as the initial cost of such equipment is significant, it requires periodic maintenance even if not used, and the fuel is not stable over long periods of time. When alcohol is added to gasoline by refineries, the alcohol tends to absorb moisture which can cause mechanical as well as operational problems with the engine. It is well known that gasoline deteriorates after six months or so and must be replaced so as to maintain the critical components thereof. The lubricating oil of the standby engine must be replaced periodically, not because the use thereof breaks down the lubricating properties, but because the time of non-use deteriorates the lubricating properties as well as allows the oil to be exposed to environmental moisture.
The efficiency of a gasoline or diesel-powered generator is compromised because such type of engine is at best 30% efficient. The efficiency is low because an internal combustion engine generates substantial heat that is dissipated to the air. The dissipation of heat from an engine is essential to the service life of the engine. A supplemental dissipation of engine heat is through the oil which circulates through the engine, and back to the oil reservoir where it is cooled somewhat. Some engines are specially equipped with oil coolers, which are like water radiators, that allow air to circulate through a separate radiator to cool the oil.
An additional shortcoming of the widespread use of standby generators is the engineering of the same for different individuals or businesses. While standby generators are widely available, they are not easily tailored to specific or specialized applications. In addition, while one can easily purchase a standby AC power unit, there is often a lack of experienced personnel who know how to modify the power delivery equipment of a home or business to make an orderly transition from the power grid to the standby unit easy and as transparent as possible. The normal person who is interested in a standby power unit does not know how many kilowatts of AC power is necessary either during normal use, or during periods of surge currents such as when large AC power-using equipment starts to operate. The proper engineering of the correct size of a standby unit must take into consideration surge capabilities as well as average power used under normal circumstances.
The acceptance of standby AC power generators by more consumers can be facilitated by making the standby units more efficient so that the initial investment is not only recovered, but recovered in a short period of time. When a standby power unit is powered by natural gas or propane gas, the cost effectiveness is enhanced, and such type of fuel does not deteriorate over time, thus eliminating the need to change out the fuel supply every year or so. Moreover, the cost of natural gas is much lower than the corresponding cost of either gasoline or diesel. When the cost of the standby unit is amortized over a period of time, together with the lower cost of fuel, and with the production of thermal energy to heat a house or business, standby units can be much more attractive and cost effective to ordinary persons. In addition to the foregoing, when AC power is available from the power grid, but thermal energy is needed to heat the premises during cold weather, the standby unit can be employed to generate heat and any excess AC power can be coupled back to the AC power grid. In many instances, the delivery of AC power back to the AC power grid can reduce the user's electricity bill from the utility, thereby providing an additional incentive to use the standby unit as often as possible.
In remote areas where electricity is not yet available, such as mountain cabins, lake houses, and the like, the availability of an AC power generator is more attractive especially when AC power can be individually provided to each house, and the thermal energy generated by the AC power unit can be used to heat the premises. In this instance, any excess AC power can be converted to DC and used to charge a bank of batteries for supplementary electrical energy for use by the user. The batteries, solar panels or wind generators can be used to generate hydrogen for use as a fuel for the engine that drives the generator. The hydrogen can be stored for use when needed by the engine.
From the foregoing, it can be seen a need exists for a standby AC power generator that is used more often to accommodate the various needs of the user and thereby make the unit more cost effective.